System and method for electronic fluid measurement

ABSTRACT

An agricultural product application implement includes a system and method for indicating an amount of fluid stored. A pressure transducer installed at the sump of a fluid tank electronically measures and displays a fluid depth. Instrumentation, such as an instrument cluster unit for the implement, is programmed via software to convert the voltage output of the pressure transducer to a volume measurement displayed in the operator&#39;s line of sight. Software within the instrument cluster unit for self-calibrating accounts for varying densities of different chemical solutions. The pressure transducer is used in conjunction with a transfer medium to prevent corrosive chemical solutions from contacting the pressure transducer.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional non-provisional patent application based on U.S.patent application Ser. No. 14/558,011, filed Dec. 2, 2014, entitled“SYSTEM AND METHOD FOR ELECTRONIC FLUID MEASUREMENT,” which is herebyincorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The invention relates generally to machines having tanks for fluidstorage, and in particular, to self-propelled sprayer applicatormachines having chemical storage tanks.

BACKGROUND OF THE INVENTION

Current methods for indicating remaining volume of a chemical solutionin, for example, a self-propelled chemical applicator typically consistsof a clear hose plumbed to fittings at the top and bottom of a tankalong with a decal calibrated by the manufacturer. Fluid volume isvisually checked by looking at the top of the fluid in the clear hoseand transposing the plane of that level onto the decal which displaysvolume.

However, due to the colorless nature of many fluids, including water,the transparency of the fluid may be nearly identical to thetransparency of the clear hose thereby making the top of the fluidcolumn difficult to view. Certain improvements have added buoyantobjects inside the tube to aid in quickly noting fluid volume. However,chemical reactions between the fluid and the clear hose, which maytypically be made from a petroleum based product, may cause the hose tobecome discolored over time, thereby once again making viewingdifficult. Other improvements have relied on electronic depthmeasurement using fuel sensors. However, taller tanks, requiring tallersensors, create high bending loads on the sensor electronics (usuallycontained at the mounting point), such as when the dynamics of the fluidcauses sloshing. These high bending loads can result in fatigue of thecircuit board connections and consequently yield an unreliable sensor.

In addition, because chemical solution tanks are typically locatedbehind an operator's station/cab, checking the remaining volume of thefluid typically requires the operator to stray 180° from the machinesforward direction. This may be ergonomically inefficient for theoperator and could potentially contribute to an unsafe operatingcondition.

A need therefore exists to provide a reliable, cost effective abilityfor indicating remaining volume of a fluid that eliminates one or moreof the foregoing disadvantages.

SUMMARY OF THE INVENTION

The present invention is directed to a system and method for indicatingan amount of fluid stored in an agricultural product applicationimplement. A pressure transducer installed at the sump of a fluid tankmay electronically measure and display a fluid depth. Instrumentation,such as the instrument cluster unit (“ICU”) for the implement, can beprogrammed via software to convert the voltage output of the pressuretransducer to a volume measurement to be displayed in the operator'sline of sight. To account for varying densities of different chemicalsolutions, software may be written within the ICU to self-calibrate theproduct density. The pressure transducer may also be used in conjunctionwith a transfer medium, such as glycerin, to prevent corrosive chemicalsolutions from contacting the pressure transducer.

Accordingly, issues with clear tube discoloration are avoided. Also,because the fluid being measured is not in contact with the sensor,reliability of the sensor due to fluid dynamics is not affected. Inaddition, accuracy of the system may be set according to accuracy of thepressure transducer.

Embodiments according to the present invention may be adaptable to awide variety of machines, storage tanks and fluids. Fluids may include,for example, chemical solutions (such as agricultural chemicalsolutions), water, fuel, oil, coolant, and so forth.

According to one aspect of the invention, a system for indicating anamount of fluid stored in a self-propelled agricultural productapplication implement may comprise: a tank with an interior volume forholding fluid; a pressure transducer disposed on a base of the interiorvolume of the tank for sensing an amount of pressure within the tankexpected by a fluid held within the tank and generating a firstelectrical signal corresponding to the amount of pressure; a controlleroperable to receive the first electrical signal to determine an amountof fluid within the tank based on the amount of pressure and theinterior volume, and to generate a second electrical signalcorresponding to the amount of fluid; and a display operable to receivethe second electrical signal and to display the amount of fluid heldwithin the tank to an operator of the implement while the operator is ina forward facing position.

According to another aspect of the invention, a transfer medium, such asglycerin, may be disposed above the pressure transducer for protectingthe pressure transducer from the fluid.

According to another aspect of the invention, the controller may beoperable to self-calibrate for differing types of fluid having differingdensities. Also, a selection source may provide an input to thecontroller for selecting a type of fluid held within the tank.

According to another aspect of the invention, a temperature sensordisposed in the interior volume of the tank, wherein the controllerfurther determines the amount of fluid based on a temperature sensedfrom within the tank. Also, a transfer medium may be disposed above thetemperature sensor for protecting the temperature sensor from the fluid.

According to another aspect of the invention, a method for indicating anamount of fluid stored in a self-propelled agricultural productapplication implement may comprise: holding a fluid within a tank havingan interior volume; sensing an amount of pressure within the tankresulting from the fluid using a pressure transducer disposed on a baseof the interior volume of the tank and communicating a first electricalsignal corresponding to the amount of pressure; determining an amount offluid within the tank based on the amount of pressure communicated bythe first electrical signal and the interior volume, and communicating asecond electrical signal corresponding to the amount of fluid; anddisplaying the amount of fluid within the tank as communicated by thesecond electrical signal to a display visible by an operator of theimplement while the operator is in a forward facing position.

Other aspects, objects, features, and advantages of the invention willbecome apparent to those skilled in the art from the following detaileddescription and accompanying drawings. It should be understood, however,that the detailed description and specific examples, while indicatingpreferred embodiments of the present invention, are given by way ofillustration and not of limitation. Many changes and modifications maybe made within the scope of the present invention without departing fromthe spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred exemplary embodiments of the invention are illustrated in theaccompanying drawings in which like reference numerals represent likeparts throughout.

FIG. 1 is a simplified cross-sectional view of a self-propelledagricultural product application implement in accordance with anembodiment of the present invention;

FIG. 2 is a simplified cross-sectional view of a tank with an interiorvolume for holding fluid in the implement of FIG. 1;

FIG. 3 is a schematic representation of a system for indicating anamount of fluid in the implement of FIG. 1; and

FIG. 4 is an exemplar calibration curve determining an amount of fluidwithin the tank in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings and specifically to FIG. 1, aspects of thepresent invention will now be described by way of an exemplarenvironment of a self-propelled agricultural product applicationimplement 10, which may be an agricultural sprayer, in accordance withan embodiment of the present invention. While an agricultural productapplication implement is shown and described, it is understood that thepresent invention is not limited to such an implement and thus may beapplicable with other types of machines including, but not limited toconstruction machines.

The implement 10 may include a frame 12 to which a pair of wing booms 14may be connected. The wing booms 14 may support a series of sprayingunits designed to deliver fluid from a tank 16 centrally supported on aframe 12, onto a farming or planting surface. The tank 16 may bepositioned generally in the center of the frame 12 between the wingbooms 14 and an operator cab 18. The tank 16 may be designed to containfluid, such as herbicide, insecticide, fertilizer, or other agriculturalchemical solutions, which may be fed to the spraying units through aseries of fluid lines as known in the art. As also known in the art, theoperator cab 18 contains an instrument cluster unit (“ICU”) or controlpanel that has various operator controls for monitoring and controllingoperation of the sprayer and its components.

Referring now to FIG. 2, a simplified cross-sectional view of the tank16 having an interior volume 20 for holding fluid 22 is provided inaccordance with an embodiment of the present invention. The fluid 22 maybe an agricultural chemical solution, however, in other embodiments, thefluid 22 could be water, fuel, oil, coolant, or any other fluid in whichdisplaying a measured volume is desirable. The tank 16 also includes anentry port 24 in which the fluid 22 may enter to fill the tank 16 and anexit port 26 in which the fluid 22 may be drawn from the tank 16 to oneor more fluid lines for use.

A pressure transducer 28 is disposed on a base 30 of the interior volume20 of the tank 16. The base 30 may be the sump of the tank 16,representing a lower area of the tank 16 relative to ground and theforce of gravity. In operation, the pressure transducer 28 senses anamount of pressure within the tank resulting from the fluid 22 heldwithin the tank 16 above the pressure transducer 28. The pressuretransducer 28 then generates an electrical pressure signal 32corresponding to the amount of pressure. The pressure transducer 28 maybe manufactured using a piezoelectric material, such as quartz, orpiezoresistive transducer mounted on a corrosive resistant diaphragm,such as stainless steel. In addition, a transfer medium 34, such asglycerin, may be disposed above the pressure transducer 28 to protectthe pressure transducer 28 from the fluid 22, such as to preventcorrosion.

A temperature sensor 38 may also be disposed in the interior volume 20of the tank 16, which may preferably be in proximity to the pressuretransducer 28. In operation, the temperature sensor 38 may sense atemperature within the tank and may generate an electrical temperaturesignal 42 corresponding to the temperature. The temperature sensor 38may be a thermocouple, thermistor, or other temperature sensing deviceas known in the art. In addition, a transfer medium 40, such asglycerin, may also be disposed above the temperature sensor 38 toprotect the temperature sensor 38 from the fluid 22, such as to preventcorrosion.

Referring now to FIG. 3, a schematic representation of a system 50 forindicating an amount of fluid in the implement 10 is provided inaccordance with an embodiment of the present invention. In the system50, the electrical pressure signal 32 and the electrical temperaturesignal 42 may be provided to an instrument cluster unit (ICU) 52, whichmay be located in the operator cab 18. The electrical pressure signal 32and the electrical temperature signal 42 may (optionally) be received bycircuitry 54, providing signal conditioning and/or buffering, and isultimately received by a controller 56. The controller 56 includes aprocessing element 58 and a data storage element 60. The data storageelement 60, which may be, for example, a rewritable non-volatile flashmemory or other non-transient medium, includes a software module 62, asystem data structure 64 and a library data structure 66. The systemdata structure 64 includes programming data values for the system,including the dimensions and interior volume of the tank 16. The librarydata structure 66 essentially provides a table providing types of fluids68 linked to corresponding densities (“ρ”) 70. The software module 62,the system data structure 64 and the library data structure 66 may beprogrammed and configured during manufacturing and may be updated fromtime to time in the field.

In operation, the controller 56 may be operable to receive theelectrical pressure signal 32 and execute the software module 62 todetermine an amount of fluid within the tank 16 based on the amount ofpressure indicated by the electrical pressure signal 32, the type offluid, such as with reference to the library data structure 66 and aselected density, and/or the interior volume, such as with reference tothe system data structure 64 and the programming data values. Thecontroller 56 may also receive the electrical temperature signal 42 andexecute the software module 62 to determine the amount of fluid withinthe tank 16 using a more precise temperature measurement. The softwaremodule 62 may apply, for example, one or more of Boyle's law,Gay-Lussac's law, Avogadro's law, the combined gas law, ideal gas lawand/or other similar laws and principles as known in the art.Accordingly, the controller is operable to generate a measurement signal72 corresponding to the amount of fluid.

A display 74 of the ICU 52 is operable to receive the measurement signal72 and display the amount of fluid held within the tank 16. The display74 is preferably positioned such that the operator of the implement 10may view the display 74 while the operator is in a forward facingposition. As a result, the need for an operator to stray 180° from themachines forward direction of travel is eliminated thereby increasingsafety. In addition, a more ergonomically efficient arrangement for theoperator is provided.

In an embodiment, the software module 62 may default to a particulartype of fluid and corresponding density. In an alternative embodiment,an input module 76 may operate to provide a selection signal 78 to thecontroller 56 for selecting, or otherwise providing data for, aparticular type of fluid and corresponding density. The input module 76could essentially be a selection source controllable by the operator viathe ICU 52.

Referring now to FIG. 4, an exemplar calibration curve 100 fordetermining an amount of fluid within the tank is provided in accordancewith an embodiment of the present invention. The calibration curve 100may be determined by the controller 56 executing the software module 62with reference to the system data structure 64 and the library datastructure 66. The calibration curve 100 may provide, for example, on afirst (“x”) axis 102 a tank head pressure, measurable in inches of water(or millibar), and on a second (“y”) axis 104, a tank volume, measurablein gallons (or liters). An equation may be expressed plotting 106 tankvolumes as a function of pressure for a particular type of fluid.Accordingly, the controller 56, upon receiving sensed values from thetank, such as the pressure and temperature from within the tank, mayaccurately determine a corresponding volume of the tank for display.

Certain terminology is used herein for purposes of reference only, andthus is not intended to be limiting. For example, terms such as “upper,”“lower,” “above,” and “below” refer to directions in the drawings towhich reference is made. Terms such as “front,” “back,” “rear,”“bottom,” “side,” “left” and “right” describe the orientation ofportions of the component within a consistent but arbitrary frame ofreference which is made clear by reference to the text and theassociated drawings describing the component under discussion. Suchterminology may include the words specifically mentioned above,derivatives thereof, and words of similar import. Similarly, the terms“first,” “second” and other such numerical terms referring to structuresdo not imply a sequence or order unless clearly indicated by thecontext.

When introducing elements or features of the present disclosure and theexemplary embodiments, the articles “a,” “an,” “the” and “said” areintended to mean that there are one or more of such elements orfeatures. The terms “comprising,” “including” and “having” are intendedto be inclusive and mean that there may be additional elements orfeatures other than those specifically noted. It is further to beunderstood that the method steps, processes, and operations describedherein are not to be construed as necessarily requiring theirperformance in the particular order discussed or illustrated, unlessspecifically identified as an order of performance. It is also to beunderstood that additional or alternative steps may be employed.

The present invention may be part of a “safety system” used to protecthuman life and limb in a field, construction or other environment.Nevertheless, the term “safety,” “safely” or “safe” as used herein isnot a representation that the present invention will make theenvironment safe or that other systems will produce unsafe operation.Safety in such systems depends on a wide variety of factors outside ofthe scope of the present invention including: design of the safetysystem, installation and maintenance of the components of the safetysystem, and the cooperation and training of individuals using the safetysystem. Although the present invention is intended to be highlyreliable, all physical systems are susceptible to failure and provisionmust be made for such failure.

Many changes and modifications could be made to the invention withoutdeparting from the spirit thereof. The scope of these changes willbecome apparent from the appended claims.

We claim:
 1. A method for indicating an amount of fluid stored in aself-propelled agricultural product application implement comprising:(a) holding a fluid within a tank having an interior volume; (b) sensingan amount of pressure within the tank resulting from the fluid using apressure transducer disposed on a base of the interior volume of thetank and communicating a first electrical signal corresponding to theamount of pressure; (c) determining an amount of fluid within the tankbased on the amount of pressure communicated by the first electricalsignal and the interior volume, and communicating a second electricalsignal corresponding to the amount of fluid; (d) displaying the amountof fluid within the tank as communicated by the second electrical signalto a display visible by an operator of the implement while the operatoris in a forward-facing position; and (e) providing a transfer mediumabove the pressure transducer for protecting the pressure transducerfrom the fluid.
 2. The method of claim 1, further comprising calibratingfor different types of fluids having differing densities based on acalibration curve.
 3. The method of claim 2, further comprisingproviding an input for selecting a type of fluid held within the tank.4. The method of claim 1, further comprising sensing a temperaturewithin the interior volume of the tank and determining the amount offluid based on the temperature sensed from within the tank.